Yeah, as you've may or may not noticed, each battle sprite has a "star level" next to it. Whatever star level is on your sprite is where you need to fight with it. When it reached 5*, it'll be useful for everything! So don't hate, just be patient.
Wait wait wait... what?
Do, 08/01/2013 - 09:58
Abelisk
starting is 0*
unprecised level, maybe 10, 1*.
15, 2*
30, 3*
50, 4*
80, 5*
it should be so. I don't really know, my drakon is level 16.